This invention relates to a radiation curable protective coating composition. More specifically, it relates to a silane free coating composition which contains an unsaturated organic compound. When applied to a substrate and radiation cured, this composition forms a protective, abrasion resistant, weather resistant, ultraviolet light resistant, transparent coating firmly held thereon. In addition, substrates coated with this composition may be tinted and/or dyed. Current markets for such coatings are well established and will expand as the abrasion resistance and weatherability of these coatings is improved.
Until recently, silanes were thought to be necessary, but costly components of all abrasion resistant coating formulations. The use of silanes, however, has been eliminated where colloidal silica dispersed in an organic solvent is used. Japanese Kokai Patent No. Sho 63[1988]-286409 issued Nov. 24, 1988, discloses a method for manufacturing a curable resin composition which contains an .alpha.,.beta.-unsaturated carboxylic acid compound and colloidal silica. These coatings, however, have one major drawback. They do not allow aqueous dispersions of colloidal silica to be used. Since aqueous dispersions of colloidal silica are, by far, the most common and readily available, a major segment of the colloidal silica market is excluded.
Commonly assigned copending U.S. application Ser. No. 07/423,159, filed Oct. 18, 1989, eliminated the costly silanes from abrasion resistant coating formulations containing aqueous dispersions of colloidal silica. The aforementioned commonly assigned application discloses silane free coating compositions which contain aqueous dispersions of colloidal silica, hydroxy acrylates and multifunctional acrylates. The present inventors have eliminated the need for hydroxy acrylates by adding unsaturated organic compounds in silane free compositions which contain aqueous dispersions of colloidal silica.